Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

Get the following msg. when I try to open Firefox: " Close Firefox. A copy of Firefox is already open. Only one copy of Firefox can be open at a time." No other copy is installed or running.

This happened

Every time Firefox opened

== After I reloaded a new copy of OS X. Previous system folder was archived.

Get the following msg. when I try to open Firefox: " Close Firefox. A copy of Firefox is already open. Only one copy of Firefox can be open at a time." No other copy is installed or running.
== This happened ==
Every time Firefox opened
== After I reloaded a new copy of OS X. Previous system folder was archived.

That may have happened because Firefox hanged or is taking to long to close. Access your task manager and terminate Firefox's application. That will loose you no data and will allow you to run Firefox again.

It's probable that it's just taking a bit longer to close, though, so waiting a bit will probably fix the issue (like a few seconds, so this for future reference).

Hello Vernon.
That may have happened because Firefox hanged or is taking to long to close. Access your task manager and terminate Firefox's application. That will loose you no data and will allow you to run Firefox again.
It's probable that it's just taking a bit longer to close, though, so waiting a bit will probably fix the issue (like a few seconds, so this for future reference).

Question owner

I have restarted, started in safe mode, fixed permissions, reinstalled FireFox. All the standard stuff.

FireFox does not show in System Monitor.

This is not a problem of FireFox taking too long to close - unless you consider three days and several restarts too long.

Clearly the answer was proposed by someone without Mac OSX experience.

...rmk

I have the same problem. Running OSX 10.6.3
I have restarted, started in safe mode, fixed permissions, reinstalled FireFox. All the standard stuff.
FireFox does not show in System Monitor.
This is not a problem of FireFox taking too long to close - unless you consider three days and several restarts too long.
Clearly the answer was proposed by someone without Mac OSX experience.
...rmk

I have the same problem, I am able to find it still running by using ps in terminal but even a kill -9 wont stop the process. A reboot will fix it but obviously thats not a very good solution.
bash# ps -ef | grep firefox
501 1885 116 0 0:00.00 ?? 0:00.00 (firefox-bin)
501 1953 1946 0 0:00.00 ttys000 0:00.00 grep firefox

Dear Vernon - this is not a matter of waiting. I believe you are on a PC. On my Mac running the current OSX and the current FF, we will get a message saying that a copy of FF is already open and that 2 copies cannot be open at the same time. It does not appear in the Mac Activty Monitor (windose task manager) and so cannot be force quit - it requires restarting the system. Essentially FF makes using the computer impossible.

Dear Vernon - this is not a matter of waiting. I believe you are on a PC. On my Mac running the current OSX and the current FF, we will get a message saying that a copy of FF is already open and that 2 copies cannot be open at the same time. It does not appear in the Mac Activty Monitor (windose task manager) and so cannot be force quit - it requires restarting the system. Essentially FF makes using the computer impossible.

Can you please try it in a new (temporary) Firefox profile and see if the issue is still present? See this article to know how to create a new Firefox profile. Please report back the results.

Can you please try it in a new (temporary) Firefox profile and see if the issue is still present? See [http://support.mozilla.com/en-US/kb/Managing+profiles this article] to know how to create a new Firefox profile. Please report back the results.

Are you sure you tried killing the right process id? “ps -ef” is a Linux/SVR4-ism and the first column is the parent process id, not the process id. On OS X and other BSD Unix system, “ps -ax” is the way to go and gives the process id in the first column.

Are you sure you tried killing the right process id? “ps -ef” is a Linux/SVR4-ism and the first column is the parent process id, not the process id. On OS X and other BSD Unix system, “ps -ax” is the way to go and gives the process id in the first column.

Helpful Reply

You can fix it on a Mac by removing the old left over folders in your Library folder:
There are folders "Firefox" and folder "Monzilla" sitting in your Library/Application folder. Trash them and reinstall Firefox and it will work.

You can fix it on a Mac by removing the old left over folders in your Library folder:
There are folders "Firefox" and folder "Monzilla" sitting in your Library/Application folder. Trash them and reinstall Firefox and it will work.

I am experiencing this issue quite frequently. I work at a school and we have approximately 150 Mac clients running Snow Leopard, from a Snow Leopard server. Many of the students are experiencing this issue on their individual server accounts, and I have found a solution by simply going into ~/Library/Application Support/Firefox/ and deleting "Profiles.ini". This causes FireFox to reset, and everything is back up and working. I have not found the EXACT cause of this, however this is something I cannot deal with on a regular basis. Do we know why this is occuring or how to prevent it?

I am experiencing this issue quite frequently. I work at a school and we have approximately 150 Mac clients running Snow Leopard, from a Snow Leopard server. Many of the students are experiencing this issue on their individual server accounts, and I have found a solution by simply going into ~/Library/Application Support/Firefox/ and deleting "Profiles.ini". This causes FireFox to reset, and everything is back up and working. I have not found the EXACT cause of this, however this is something I cannot deal with on a regular basis. Do we know why this is occuring or how to prevent it?

SECOND THAT - Maddakadam's advice is what finally worked for me. (AS WELL)

But the only reason I had this problem was because I got a message saying "This is not the latest version of FF, update..." so I did... and that was bad because my 5YO PB G4 can't run the newest FF. *** SO WHY DOES FF TELL ME TO UPGRADE? ***

Once I did, trouble all the way, my Mac crashed so bad I had to take it to the shop... easy fix but just the same it's horrible way for an app to act... why propose an upgrade when you don't have the system and my Mac CAN'T! run the system! WhY NOt just tell me that I can upgrade if I get the following OS!. INFORM ME!

SECOND THAT - Maddakadam's advice is what finally worked for me. (AS WELL)
But the only reason I had this problem was because I got a message saying "This is not the latest version of FF, update..." so I did... and that was bad because my 5YO PB G4 can't run the newest FF. *** SO WHY DOES FF TELL ME TO UPGRADE? ***
Once I did, trouble all the way, my Mac crashed so bad I had to take it to the shop... easy fix but just the same it's horrible way for an app to act... why propose an upgrade when you don't have the system and my Mac CAN'T! run the system! WhY NOt just tell me that I can upgrade if I get the following OS!. INFORM ME!

Helpful Reply

I got this message after trying to copy my profile folder over to a new computer

This worked for me:
make sure hidden files can be seen
go to (user)/Library/Application Support/Firefox
find profiles.ini
open it with textedit and make sure the default profile is the same folder you have under Firefox/Profiles
good luck!

I got this message after trying to copy my profile folder over to a new computer
This worked for me:
make sure hidden files can be seen
go to (user)/Library/Application Support/Firefox
find profiles.ini
open it with textedit and make sure the default profile is the same folder you have under Firefox/Profiles
good luck!

i'm running mac osx 10.6.8. i got the same message upon attempting to invoke firefox. i discovered that there was a zombie executable still running of firefox which wouldn't display anything, yet had a PID. there is clearly some kind of bug keeping FF open, but a workaround "fix" i used was-

this works. my take is that there is some form of garbage collection bug that allows a FF to stay open as a zombie in background, disabling you from invoking it.

i'm wondering if this is potentially some form of virus that has infected FF on macs? this was the first time my mac/ firefox has done this, ever....

anyone else have this paranoid hunch?

best regards,
svbv-dan

i'm running mac osx 10.6.8. i got the same message upon attempting to invoke firefox. i discovered that there was a zombie executable still running of firefox which wouldn't display anything, yet had a PID. there is clearly some kind of bug keeping FF open, but a workaround "fix" i used was-
# open the terminal app
# do a ps -ax
# locate the firefox zombie, on my box, it was-
# 8030 ?? 0:43.44 /Applications/Firefox 4 Beta/Firefox 4.0b7.app/Contents/MacOS/firefox -psn_0_2
# identify its process ID (PID)
# do a kill -9 PID, which in this case was-
# kill -9 8030
# re-invoke firefox
this works. my take is that there is some form of garbage collection bug that allows a FF to stay open as a zombie in background, disabling you from invoking it.
i'm wondering if this is potentially some form of virus that has infected FF on macs? this was the first time my mac/ firefox has done this, ever....
anyone else have this paranoid hunch?
best regards,
svbv-dan

I got the message after deleting the Mozilla and Firefox folders located in Applications Support folder, I have already tried all the possibilities posted but none is working. Even if I show the hidden files, Terminal is not able to find .parentlock neither in the ps -ax command or Activity Monitor show any trace of FF.

Any other idea that can help? Thanks!

I got the message after deleting the Mozilla and Firefox folders located in Applications Support folder, I have already tried all the possibilities posted but none is working. Even if I show the hidden files, Terminal is not able to find .parentlock neither in the ps -ax command or Activity Monitor show any trace of FF.
Any other idea that can help? Thanks!

My issue is if I have Firefox already open, and I go to Microsoft Outlook and click on any email that has a html link in it, the problem being that nothing happens when I click on it unless I close the already opened Firefox browser.

My issue is if I have Firefox already open, and I go to Microsoft Outlook and click on any email that has a html link in it, the problem being that nothing happens when I click on it unless I close the already opened Firefox browser.

Before you start blowing away your profile (which is a real pain if you have lots of preferences/bookmarks, etc. to recover), just check in case you have been left with a leftover "lock" file.
To check, open a terminal and change directory to your firefox account data,

cd Library/Application Support/Firefox/Profiles

Then remove any leftover lock files (be careful with the command, type it exactly, don't forget the "." character)

rm */.parentlock

try staring firefox again

Before you start blowing away your profile (which is a real pain if you have lots of preferences/bookmarks, etc. to recover), just check in case you have been left with a leftover "lock" file.
To check, open a terminal and change directory to your firefox account data,
cd Library/Application Support/Firefox/Profiles
Then remove any leftover lock files (be careful with the command, type it exactly, don't forget the "." character)
rm */.parentlock
try staring firefox again

I forgot to come back here and say that I indeed found a solution to this.

1. Launch My Computer or Windows Explorer.
2. Choose menu 'Tools' -> 'Folder Options'
3. Click the 'File Types' tab.
4. Scroll down to find 'URL:HyperText Transfer Protocol' (under the File Types column) and make sure it's highlighted.
5. Click the 'Advanced' button.
6. In the 'Actions' box make sure that 'open' is highlighted (click on it if necessary)
7. Click the 'Edit' button.
8. Uncheck 'Use DDE', click the Browse button and browse to Firefox.exe on your system, and click OK. [Updated for clarification, sorry about the earlier omission.] If you get a "file not found" message, browse to Firefox.exe and click OK.
9. The path to Firefox.exe should now appear in the 'Application used to perform this action' box.
10. Go to that 'Application used to perform this action' box, and add '-url "%1"' at the end, without the single quotes, so that it reads e.g. (on my computer at least) "C:\Program Files\Mozilla Firefox\firefox.exe" -url "%1" - with the double quotes!
10. Click OK again.
11. Repeat the process with the file type 'URL:HyperText Transfer Protocol with Privacy'

I forgot to come back here and say that I indeed found a solution to this.
1. Launch My Computer or Windows Explorer.
2. Choose menu 'Tools' -> 'Folder Options'
3. Click the 'File Types' tab.
4. Scroll down to find 'URL:HyperText Transfer Protocol' (under the File Types column) and make sure it's highlighted.
5. Click the 'Advanced' button.
6. In the 'Actions' box make sure that 'open' is highlighted (click on it if necessary)
7. Click the 'Edit' button.
8. Uncheck 'Use DDE', click the Browse button and browse to Firefox.exe on your system, and click OK. [Updated for clarification, sorry about the earlier omission.] If you get a "file not found" message, browse to Firefox.exe and click OK.
9. The path to Firefox.exe should now appear in the 'Application used to perform this action' box.
10. Go to that 'Application used to perform this action' box, and add '-url "%1"' at the end, without the single quotes, so that it reads e.g. (on my computer at least) "C:\Program Files\Mozilla Firefox\firefox.exe" -url "%1" - with the double quotes!
10. Click OK again.
11. Repeat the process with the file type 'URL:HyperText Transfer Protocol with Privacy'